Arguments

Description

These ioctls are deprecated.
New drivers and applications should use
JPEG class controls for image quality and JPEG markers control.

[to do]

Ronald Bultje elaborates:

APP is some application-specific information. The
application can set it itself, and it'll be stored in the JPEG-encoded
fields (eg; interlacing information for in an AVI or so). COM is the
same, but it's comments, like 'encoded by me' or so.

jpeg_markers describes whether the huffman tables,
quantization tables and the restart interval information (all
JPEG-specific stuff) should be stored in the JPEG-encoded fields.
These define how the JPEG field is encoded. If you omit them,
applications assume you've used standard encoding. You usually do want
to add them.